Osmotic systems in the form of osmotic devices for delivering a beneficial agent to an environment of use are known to the art in U.S. Pat. Nos. 3,845,770 and 3,916,899. The systems disclosed in these patents are made with a wall that surrounds a compartment containing an agent. The wall is permeable to an external fluid, substantially impermeable to agent, and has a passageway for delivering agent. These systems are extraordinarily effective for delivering an agent that is soluble in the fluid and exhibits an osmotic pressure gradient across the wall against the fluid, and also for delivering an agent that has limited solubility in the fluid and is mixed with an osmotically effective compound that is soluble in the fluid and exhibits an osmotic pressure gradient across the wall against the fluid. The systems release agent by fluid being continuously imbibed through the wall into the compartment at a rate determined by the permeability of the wall and the osmotic pressure gradient across the wall to produce a solution of soluble agent, or a solution of soluble compound containing agent which solution in either operation is dispensed at a controlled and continuous rate over a prolonged period of time. While the above systems represent an outstanding and pioneer advancement in the delivery art, and while they are useful for dispensing innumerable agents to an environment of use, it has now been found the systems can have a laminated wall that unexpectedly improves the usefulness and integrity of the systems.
That is, the systems can have a laminated wall that permits properties such as permeability to fluids, impermeability to agents and compounds, and physical and chemical integrity be selected independently, and also have the mode of agent release made programmable based on the laminae comprising the wall. For example, the wall can comprise a laminae consisting of a lamina facing a compartment and a lamina facing an environment with each possessing different properties. The lamina facing the compartment housing ingredients such as agents, osmotic compounds and solutions thereof, that can slowly attack and cause the lamina to loose its integrity can be made inert by formulating it with materials resistant to attack therefrom, while the lamina facing the environment can be formed of different materials inert to the environment, and which lamina optionally is not contacted by the ingredients, and if it is exposed thereto, it does not interact therewith.